1. Technical Field
This disclosure relates to methods and resins for creating electrically-conductive objects. This disclosure relates to composites comprising forms of nanocarbon. This disclosure particularly relates to composites comprising carbon nanotubes. This disclosure also particularly relates to composites comprising graphene, and to nanodiamonds, and to other forms of nanocarbon. This disclosure also particularly relates to three-dimensional printing systems and/or devices comprising the any of the various forms of nanocarbon. This disclosure also particularly relates to ultraviolet- or visible-radiation or electron-beam photocurable materials containing any of the various forms of nanocarbon. This disclosure also particularly relates to fibers and filaments containing any of the various nanocarbon forms on their surfaces and/or within their interior. This disclosure particularly relates to systems and/or devices comprising these nanocarbon materials and/or composites.
2. Description of Related Art
The polymerization of chemical monomers can be accomplished by any of a number of mechanisms, including heat, sound, and electromagnetic radiation such as light, electron beams, and microwaves, among many other methods well known to those skilled in the art.
Three-dimensional (3-D) printing refers to a family of additive technologies for building 3-D solid or partially-solid objects by sequentially or simultaneously depositing layers of materials according to a design produced using a computer-aided design (CAD) software application. This technology can be used to create highly-customized complex parts and products that are difficult or impossible to manufacture using traditional technologies. This technology can also be used to rapidly create prototype objects which could take much longer to produce by other means. This technology can also be used to create objects at a lower cost than they could be produced using other means.
There are several major 3-D printing technologies differing mainly in the way successive layers are built to create the final 3-D object. Some methods use melting or softening and deposition of a material (referred to generally as the ‘build material’) to produce the layers of the growing object. For example, selective laser sintering (SLS) works by laying down a thin layer of powdered metal, plastic, ceramic, or glass and then sintering the intended cross-sectional area of each layer to produce the desired object. Powder printing works similarly, except that the layers of powdered materials which are laid down are then printed over using a technology such as an ink-jet printer to create the cross-sectional image of the desired object. Fused-deposition modeling (FDM) works by extruding melted plastic or metal, often supplied in the form of filaments or wires, through an extrusion nozzle to form the successive layers. Stereolithography (or stereolithographic assembly, SLA) is based on curing (polymerizing) liquid materials such as photopolymer resins by applying external energy sources such as ultraviolet (UV) or visible light or electron-beam irradiation to produce each successive layer of a solid object.
A current challenge for the field of 3-D printing is improving the available 3-D printing materials to impart specific properties and versatility which are needed for the ever-expanding range of applications.
Another major challenge for the 3-D printing industry is the lack of efficient electrically-conducting materials with can be employed in 3-D printing and other additive manufacturing and photocurable processes. The ability to reproducibly fabricate electrically-conducting objects using 3-D printing techniques would enable a wide array or new and novel products, including for example electronic devices, energy-storage devices, communications devices, medical devices, aircraft and aerospace vehicles, and numerous other objects which are currently unavailable.
Nanocarbon materials (“nanocarbons”) include all forms of carbon in which at least one dimension is smaller than about 1 micrometer (μm). These can include, but are not limited to, single-walled carbon nanotubes (CNT), multi-walled CNT, graphenes (GR), fullerenes (FL), nanodiamond, and all other nanoscale carbon forms.
Addition of nanocarbons and their mixtures in various proportions and combinations to metal, plastic, ceramic (including glasses), polymers (including photopolymers), and other 3-D printable materials may lead to formation of nanocarbon composites with increased electrical conductivity, increased thermal conductivity, increased mechanical strength, and other improvements in properties.
A major challenge in this task has long been considered to be ensuring a sufficiently high degree of dispersion of the nanocarbon component in the nanocarbon composite material, since it was believed that only well-dispersed nanocarbons would impart useful properties. Typically, nanocarbon agglomeration results in under-utilization of the potential of the composite nanocarbon material and degraded properties of the product.
A second major challenge is preventing physical, chemical, structural, or other damage to nanocarbons during the process of fabrication of nanocarbon composites. Typically, damaged nanocarbons exhibit inferior properties when incorporated into composite materials.
For further disclosures related to nanocarbon 3-D printing materials including nanocarbon oxides), for example, see the following publications: M. N. dos Santos, C. V. Opelt, S. H. Pezzin, C. A. C. E. da Costa, J. C. Milan, F. H. Lafratta, and L. A. F. Coelho, Nanocomposite of photocurable epoxy-acrylate resin and carbon nanotubes: dynamic-mechanical, thermal and tribological properties, Materials Research, 16 (2), 367-374 (2013); M. Sangermano, E. Borella, A. Priola, M. Messori, R. Taurino, and P. Potschke, Use of single-walled carbon nanotubes as reinforcing fillers in UV-curable epoxy systems. Macromolecular Materials and Engineering, 293(8), 708-713 (2008); Y. F. Zhu, C. Ma, W. Zhang, R. P. Zhang, N. Koratkar, and J. Liang, Alignment of multiwalled carbon nanotubes in bulk epoxy composites via electric field. Journal of Applied Physics, 105(5), 1-6 (2009); M. Martin-Gallego, M. Hernandez, V. Lorenzo, R. Verdejo, M. A. Lopez-Manchado, and M. Sangermano, Cationic photocured epoxy nanocomposites filled with different carbon fillers. Polymer, 53(9), 1831-1838 (2012); M. N. dos Santos, C. V. Opelt, F. H. Lafratta, Lepienski C M, S. H. Pezzin, and L. A. F. Coelho, Thermal and mechanical properties of a nanocomposite of a photocurable epoxy-acrylate resin and multiwalled carbon nanotubes, Materials Science and Engineering A: Structural Materials Properties Microstructure and Processing, 528(13-14), 4318-4324 (2011); F. H. Gojny, M. H. G. Wichmann, U. Kopke, B. Fiedler, and K. Schulte, Carbon nanotube-reinforced epoxy-compo sites: enhanced stiffness and fracture toughness at low nanotube content, Composites Science and Technology, 64(15), 2363-2371 (2004); B. Dong, Z. Yang, Y. Huang, and H. L. Li, Study on tribological properties of multi-walled carbon nanotubes/epoxy resin nanocomposites, Tribology Letters, 20(3-4), 251-254 (2005); S. Ushiba, S. Shoji, K. Masui, P. Kuray, J. Kona, and S. Kawata, 3D microfabrication of single-wall carbon nanotube/polymer composites by two-photon polymerization lithography, Carbon 59, 283-288 (2013). The entire content of these publications is incorporated herein by reference.
A variety of nanocarbon materials (i.e. single-walled, double-walled, and multi-walled CNTs, graphene, nanodiamonds, etc.) are commercially available as dry powders and/or suspensions. CNT nanocarbon materials may be synthesized by a variety of CNT synthesis methods known to those skilled in the art. Some examples of CNT synthesis methods include arc-discharge, laser-vaporization, and chemical vapor deposition (CVD), as are described for example in publications such as M. Kumar and Y. Ando, Chemical Vapor Deposition of Carbon Nanotubes: A Review on Growth Mechanism and Mass Production, Journal of Nanoscience and Nanotechnology, vol. 10, pp. 3739-3758 (2010); G. L. Hornyak, L. Grigorian, A. C. Dillon, P. A. Parilla, K. M. Jones, and M. J. Heben, A Temperature Window for Chemical Vapor Decomposition Growth of Single-Wall Carbon Nanotubes, Journal of Physical Chemistry B, vol. 106, pp. 2821-2825 (2002); L. Grigorian, G. L. Hornyak, A. C. Dillon, and M. J. Heben, Continuous growth of single-wall carbon nanotubes using chemical vapor deposition, U.S. Pat. No. 7,431,965, Oct. 7, 2008. The entire content of these publications is incorporated herein by reference.
The arc-discharge method employs evaporation of metal-catalyzed graphite electrodes in electric arcs that involve very high (about 4,000° C.) temperatures. The laser-vaporization method employs evaporation of a graphite target by lasers in conjunction with high-temperature furnaces. These two methods operate in batch mode and may therefore be poorly suited to high-volume, low cost production. The CVD method is based on decomposition of carbon-containing gases on supported catalyst and may offer the more efficient, low-cost, and scalable method of producing CNTs. Currently, most commercial CNT materials are manufactured by the CVD method.
Thus, the ability to disperse nanocarbon forms adequately in materials which are suitable for 3-D printing in such as way as to obtain electrically-conducting materials and 3-D printed objects would be expected to enable a large number of new and novel products in a wide array of fields and industries.